Method and apparatus for reducing intraocular pressure

ABSTRACT

An intraocular drainage apparatus for treatment of glaucoma, a device to be used in the insertion of the drainage apparatus, and a method of controllably regulating intraocular pressure in glaucoma patients through the use of the drainage apparatus is described herein. The drainage apparatus is comprised of a tube capable of conducting fluid disposed between an inlet assembly, where aqueous humor enters the apparatus, and an outlet assembly, where aqueous humor exits the apparatus. The inlet assembly is comprised of a beveled tip and preferably an anchor. The beveled tip allows the drainage apparatus to be more easily inserted into an eyeball and the anchor, when employed, functions to hold the beveled tip of the inlet assembly within the anterior chamber of the eyeball. An opening in the beveled tip of the inlet assembly allows aqueous humor from the anterior chamber of the eyeball to flow through the inlet assembly, through the tube to ultimately drain through the outlet assembly, situated on the external surface of the eyeball, so as to be drained out of the eyeball onto the exterior surface of the eyeball. The inserting apparatus is comprised of an insertion prong attached to a first handle. The insertion prong has a sharp, beveled insertion point. The insertion prong also defines an aperture wherein a second prong is slideably received. The drainage apparatus is seated in the inserting apparatus and is positioned at a proper point in the eyeball. The inserting apparatus is then manipulated so that the second prong drives the drainage apparatus into the proper position within the eyeball. The drainage apparatus also provides for the use of micropore filters and/or valves to prevent infection and/or to predictably regulate the flow of aqueous humor from the anterior chamber of the eyeball to the surface of the eyeball, thereby allowing for post-surgical adjustment of the intraocular pressure within the eyeball. An apparatus for removing and replacing these filters and/or valves is also disclosed, as are alternative embodiments of the drainage apparatus and inserting apparatus.

TECHNICAL FIELD

The present invention relates to the field of medical technology,particularly to an apparatus to be implanted in an eyeball for thetreatment of glaucoma.

BACKGROUND OF THE INVENTION

Glaucoma is one of the leading causes of blindness in the United States.It is estimated that two to three million people in the United Stateshave some degree of visual loss resulting from glaucoma. While glaucomais a medical condition which can be caused by several factors, excessiveintraocular pressure is a major risk factor for developing glaucoma.Over time, excessive intraocular pressure can cause damage to the opticnerve resulting in gradual loss of vision and, in some cases, blindness.Excessive intraocular pressure is caused by an increase in theresistance to outflow of fluid, called aqueous humor, in the anteriorchamber of the eyeball, which can be caused by a number of differentfactors including injury, the aging process, reaction to medication(such as corticosteroids), structural abnormalities within the eyeball,and a genetic predisposition.

Aqueous humor is a clear, watery fluid which is constantly circulatedwithin the anterior chamber of the eyeball. It serves to nourish thecornea and lens and to provide the intraocular pressure necessary tomaintain the shape of the eyeball. Aqueous humor exits the anteriorchamber through a network of spongy tissue called the trabecularmeshwork, which is located in the intersecting space (the angle) betweenthe iris and the cornea. Increased intraocular pressure results whenaqueous humor cannot drain properly or at an appropriate rate throughthe trabecular meshwork or other outflow pathways. The only proventreatment for glaucoma is to reduce intraocular pressure.

Increased intraocular pressure can in some cases be treated withappropriate medication. These medications are usually administeredthrough pills or eye drops and work to either decrease the rate at whichaqueous humor flows into the eyeball, or to increase the rate at whichaqueous humor drains from the eyeball. However, as with any medication,patients experience different levels of response to the medication, andthe side effects of some medications can become intolerable in certainindividuals.

Surgical procedures are also employed to treat glaucoma. Certainprocedures are referred to as “filtration” procedures, since the endgoal of these particular surgical procedures is to increase the outflowof aqueous humor from the anterior chamber, thereby reducing intraocularpressure. Procedures focused on increasing the outflow of aqueous humorfrom the anterior chamber of the eyeball are theoretically morebeneficial than those designed to decrease the production of aqueoushumor, as over 95% of glaucomatous disease is a consequence of increasedoutflow resistance or reduced outflow rate rather than increased aqueoushumor production or increased venous pressure distal to the outflowchannels. Full thickness filtration surgical procedures involve thecreation of an alternate route for the aqueous humor to flow from theanterior chamber of the eyeball into the subconjuctival space with theformation of a bleb—an area of limbal (anterior) filtration—whichcontains the aqueous humor. Guarded filtration surgical procedures, suchas a trabeculectomy, involve the surgical creation of an opening whichis covered by partial thickness sclera, from the anterior chamber intothe subconjunctival space, thereby resulting in increased aqueous humorflow out of the anterior chamber. Unfortunately, the failure rate offiltration procedures is unacceptably high. In addition, postoperativeintraocular pressure is almost always unstable and unpredictable.Initial overdrainage can lead to abnormally low intraocular pressure,known as hypotony, which can cause the eyeball to malfunction and delaythe patient's postoperative recovery. Also, scarring or excessiveresistance may occur in the subconjunctival, episcleral, or scleralregions (i.e. the sclerostomy site or surgical opening into the anteriorchamber), thereby restricting the drainage.

Surgical procedures have also been used to reduce the amount of aqueoushumor production within the eyeball. Ciliodestructive surgery, alsoknown as cyclocryotherapy or cyclophotocoagulation, involves the use ofeither cryotherapy or a laser on the surface of the eyeball to reducethe production of aqueous humor. However, this procedure can cause adecrease in vision, and is usually used as a last resort when otherprocedures have failed.

Another method of treating intraocular pressure involves the use ofdrainage devices implanted within the anterior chamber as a means todrain aqueous humor while maintaining proper intraocular pressure. Thesedevices typically incorporate a tube situated within the anteriorchamber which drains aqueous humor from the anterior chamber into asurgically created posterior reservoir, called a fibrous capsule, formedaround the scleral explant of the device. The aqueous humor which drainsinto the fibrous capsule is eventually resorbed by the body. Some ofthese drainage devices employ valve mechanisms to provide resistance toaqueous humor outflow. These valves have been shown to be unpredictablein their performance, resulting in excessive outflow of aqueous humorand possible hypotony. The valves can also become clogged and cease tofunction altogether, which results in an increase in intraocularpressure. Also, the fibrous capsule can become scarred or can developexcessive resistance, resulting in failure and a need for surgicalrevision. In addition, the insertion process for properly implantingthese drainage devices within the eyeball can often be very complex andtime consuming, increasing the duration of the surgical procedure itselfand the postoperative recovery period for the patient.

Certain drainage devices have been developed to reduce intraocularpressure by draining aqueous humor from the anterior chamber to theexternal surface of the eyeball, as shown by U.S. Pat. No. 5,346,464 toCamras (see also U.S. Pat. No. 6,595,945 to Brown, U.S. Pat. No.4,886,488 to White, U.S. Pat. No. 5,743,868 to Brown and U.S. Pat. No.5,807,302 to Wandel). These drainage devices have the added benefit ofnot requiring the creation of a bleb or fibrous capsule for drainage.Therefore, the surgical outcome is not influenced by the possibility ofsubconjunctival scarring. The devices described in the prior art havenot eliminated potential problems such as difficulty of properinsertion, failure of the device, unpredictable postoperativeintraocular pressure without a means to compensate or adjust the devicefor optimal results, and/or extended postoperative recovery time.Additionally, some of these devices do not adequately guard against thepotential for infection by entry of microorganisms either through oraround the device.

There exists a need in the art for a means to treat glaucoma which ispredictable, which allows for the post-surgical adjustment ofintraocular pressure, which results in long-term efficacy, which limitsthe risk of infection, which is comfortable for the patient, and whichcan be properly inserted both quickly and easily. The present inventionmeets these needs.

SUMMARY OF THE INVENTION

It is a general object of the present invention to disclose a novelapparatus and method for the treatment of glaucoma.

It is another object of the present invention to provide for a methodfor using the apparatus to treat glaucoma, involving the insertion ofthe apparatus into an eyeball and securing the apparatus within and uponsaid eyeball such that the flow of aqueous humor from the anteriorchamber of an eyeball to the external surface of said eyeball iscontrollable so as to maintain a desirable intraocular pressure.

It is yet another object of the present invention to provide for a toolto insert the apparatus in an eyeball.

It is still another object of the present invention to provide for amethod to replace a filter or valve in the apparatus so as to preventinfection and to control the flow of aqueous humor through theapparatus.

Accordingly, the present invention provides for an apparatus to beimplanted in an eyeball comprised of a tube having an inlet assembly andan outlet assembly; said outlet assembly being positioned on theexternal surface of the eyeball; securing means formed upon said inletassembly, said securing means being capable of securing said inletassembly within said anterior chamber of the eyeball; and flow controlmeans contained within said outlet assembly to allow the flow of aqueoushumor through said apparatus from said anterior chamber of the eyeballto the exterior surface of the eyeball to be controllably regulated tomaintain a desired and predictable intraocular pressure.

Additional objects, advantages and novel features of the presentinvention will be set forth in part in the description which follows,and in part will become apparent to those skilled in the art uponexamination of the following, or may be learned from practice of theinvention.

DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of this specification andare to be read in conjunction therewith and in which like referencenumerals are used to indicate like parts in the various views:

FIG. 1 is a perspective view of a drainage apparatus according to thepresent invention.

FIG. 2 is a cross-sectional view of the outlet assembly of the drainageapparatus and filter with the outer member removed.

FIG. 3 is a cross-sectional view of the outlet assembly of the drainageapparatus and filter with the outer member attached to the inner member.

FIG. 4 is a perspective view of the outlet assembly of the drainageapparatus, parts broken away to reveal details of construction.

FIG. 5 is a cross-sectional view of an eyeball showing the drainageapparatus inserted therein.

FIG. 6 is a cross-sectional view of the outlet assembly of the drainageapparatus and valve.

FIG. 7 is a cross-sectional view of the outlet assembly of the drainageapparatus with a suctioning device attached to the outer member andinserting it upon the inner member.

FIG. 8 is a perspective view of a device to insert a drainage apparatusinto an eyeball.

FIG. 9 is a perspective view of the drainage apparatus seated in thedevice to insert the drainage apparatus into an eyeball.

FIG. 10 is a perspective view of a device for inserting a drainageapparatus into an eyeball, a drainage apparatus, and an eyeball at thepoint of insertion into the eyeball.

FIG. 11 is a cross-sectional view of another embodiment of the drainageapparatus.

FIG. 12 is a perspective view of an eyeball into which a drainageapparatus has been inserted.

FIG. 13 is a perspective view of a device for stabilizing a drainageapparatus to allow for the removal and replacement of valves or filterswithin the drainage apparatus.

FIG. 14 is a perspective view of the drainage apparatus with apericardial patch secured to the tube and insertion plate of theapparatus.

FIG. 15 is a perspective view of another embodiment of a device forinserting a drainage apparatus into an eyeball, parts broken away toreveal details of construction and operation.

DESCRIPTION OF THE INVENTION

The present invention provides for a method and apparatus to directaqueous humor from the anterior chamber of an eyeball to the externalsurface of the eyeball as a means to predictably regulate intraocularpressure and treat glaucoma. An embodiment of a drainage apparatus 20according to the present invention is illustrated in FIG. 1. As shown inFIG. 1, the drainage apparatus 20 comprises an inlet assembly 24 havinga first end 50 and a second end 51, a tube 22 capable of conductingaqueous humor having a first end 53 and a second end 55, and an outletassembly 26.

The inlet assembly 24 is further comprised of a beveled tip 28 formed atthe first end 50 of the inlet assembly 24, and an insertion plate 74formed near the second end 51 of the inlet assembly 24. An opening 32 isformed through the inlet assembly 24 allowing aqueous humor to flowthrough the inner lumen of the inlet assembly 24. An anchor 30 may alsobe formed near the first end 50 of the inlet assembly 24.

The second end 51 of the inlet assembly 24 is connected to the first end53 of the tube 22. The tube 22 is capable of conducting aqueous humorthrough its inner lumen. The second end 55 of the tube 22 is connectedto the outlet assembly 26.

As shown in FIGS. 2 and 3, the outlet assembly 26 is comprised of anouter member 34 and an inner member 36. The outer member 34 furthercomprises a central chamber 42 having at least one aperture 19, a filter52 and a flange 40 disposed along the outer aspect of the centralchamber 42. The inner member 36 comprises a central cavity 46, a groove44 formed therein, and a plurality of spacers 48.

The shape of the beveled tip 28 of the inlet assembly 24 allows thefirst end 50 and opening 32 of the inlet assembly 24 to be more easilyinserted into the anterior chamber 80 of an eyeball 76 during theprocess of inserting the drainage apparatus 20 into an eyeball 76described in detail below. An anchor 30 may be disposed on the outeraspect near the first end 50 of the inlet assembly 24. In this position,the anchor 30 will help to secure the beveled tip 28 of the first end 50of the inlet assembly 24 within the anterior chamber 80 of the eyeball76. Alternatively, a plurality of anchors may be formed on the outeraspect of the first end 50 of the inlet assembly 24, thereby allowingthe first end 50 of the inlet assembly 24 to be secured at a number ofdifferent lengths within the anterior chamber 80 as may be necessary incertain afflicted eyeballs.

In the preferred embodiment, inlet assembly 24 and tube 22 are formed asone unit. In other embodiments, inlet assembly 24 and tube 22 may beformed separately from the same or different materials. When formedseparately, the second end 51 of the inlet assembly 24 is attached tothe first end 53 of the tube 22. The tube 22 may be formed such that theinner diameter of the first end 53 of the tube 22 is slightly smallerthan the outer diameter of the second end 51 of the inlet assembly 24.This allows the second end 51 of the inlet assembly 24 to be insertedinto the first end 53 of the tube 22, so that the second end 51 of theinlet assembly 24 and the first end 53 of the tube 22 are held togetherby a frictional fit. Other known methods of attaching the first end 53of the tube 22 to the second end 51 of the inlet assembly 24 may also beemployed for this purpose.

As shown in FIGS. 2 and 3, both the outer member 34 and inner member 36of the outlet assembly 26 are preferably round and convex in shape,similar to a contact lens, thereby allowing the outlet assembly 26 ofthe drainage apparatus 20 to sit comfortably on the external surface ofthe conjunctival layer 82 of the eyeball 76 after insertion. While thisparticular shape is preferable because it helps provide comfort to thepatient, other shapes for both the outer member 34 and inner member 36may also be used with the drainage apparatus 20.

The second end 55 of the tube 22 is connected to the inner member 36 ofthe outlet assembly 26. The tube 22 and the inner member 36 may beformed as a single unit and may be comprised of the same material.Alternatively, the tube 22 and the inner member 36 may be formedseparately and secured to each other by a frictional fit as describedabove or through other methods suitable for this purpose.

A central cavity 46 is formed in the center of the inner member 36. Thecentral chamber 42 of the outer member 34 is received within the centralcavity 46. The groove 44 formed within the central cavity 46 serves toreceive the flange 40 disposed along the outer aspect of the centralchamber 42, thereby securing the central chamber 42 within the centralcavity 46. This also serves to secure the outer member 34 to the innermember 36. As shown in FIG. 3, the central chamber 42 may also extendslightly into the tube 22, further helping to secure the outer member 34to the inner member 36 by a frictional fit between the tube 22 and thecentral chamber 42. A gap between the outer member 34 and inner member36 is maintained by the plurality of spacers 48 formed in the innermember 36. FIG. 4 illustrates one embodiment of the spacers 48 withinthe inner member 36.

The central chamber 42 of the outer member 34 contains a microporefilter 52. As shown in FIG. 3, when the outer member 34 is secured tothe inner member 36, the filter 52 is positioned adjacent to the secondend 55 of the tube 22. Aqueous humor flowing from the tube 22 into theoutlet assembly 26 is thereby directed through the filter 52. The filterprovides resistance to the flow of aqueous humor from the tube 22 intothe outlet assembly 26. A filter of greater density (having a smallerpore diameter) will result in increased flow resistance, therebydecreasing the flow of aqueous humor through the drainage apparatus 20and providing for a higher intraocular pressure. A filter of lesserdensity (having a larger pore diameter) will result in decreased flowresistance, thereby increasing the flow of aqueous humor through thedrainage apparatus 20 and providing for a lower intraocular pressure. Inaddition, the filter 52 serves as a barrier to microbial infection.

After passing through the filter, the aqueous humor flows out of thecentral chamber 42 though the apertures 19. The aqueous humor then flowsbetween the spacers 48 into the gap between the outer member 34 andinner member 36. The aqueous humor then drains out of the outletassembly 26 onto the external surface of the conjunctival layer 82 ofthe eyeball 76.

Another embodiment of the present invention is illustrated in FIG. 11and provides for a drainage apparatus 25 incorporating a one-pieceoutlet assembly 27. The one-piece outlet assembly 27 is comprised of afirst member 29 and a second member 31 which are affixed to each otherby means of a chamber 57 and spacers 48. The chamber 57 houses a filter52 and also contains apertures 19 through which aqueous humor can flowto exit the chamber 57. A plurality of spacers 48 are disposed betweenthe first member 29 and the second member 31, and serve to maintain agap between the two so as to allow aqueous humor to flow out of theone-piece outlet assembly 27 onto the external surface of theconjunctival layer 82 of an eyeball 76. Both the first member 29 andsecond member 31 are optimally round and convex in shape, similar to acontact lens, so as to comfortably fit the external curvature of aneyeball 76. While this shape is beneficial and helps provide comfort tothe patient, other shapes for both the first member 29 and second member31 may also be used with the one-piece outlet assembly 27.

A coupling mechanism 33 is formed on the second member 31 and serves toattach the second end 55 of the tube 22 to the one-piece outlet assembly27. The coupling mechanism 33 is received within the second end 55 ofthe tube 22 and is held therein by a frictional fit. The couplingmechanism is hollow, thereby allowing aqueous humor to flow through itsinner lumen. The filter 52 is disposed between the coupling mechanism 33and the apertures 19 within the central chamber 57. The filter providesresistance to the flow of aqueous humor from the tube 22 into theone-piece outlet assembly 27 as described above.

Aqueous humor flows from the tube 22 through the coupling mechanism 33and is directed through the filter 52. After passing through the filter52, the aqueous humor flows through the apertures 19 of the chamber 57,into the area between the spacers 48. The aqueous humor then exits theone-piece outlet assembly 27 by flowing through the gap between thefirst member 29 and second member 31, thereby draining onto the externalsurface of the conjunctival layer 82 of the eyeball 76.

As illustrated in FIG. 6, a valve 91 may also be employed to provideresistance to the flow of aqueous humor through drainage apparatus 20 or25. When a valve 91 is employed in drainage apparatus 20 or 25, a filter52 is still required to prevent the ingress of microorganisms, but thefilter itself does not provide sufficient resistance to the outflow ofaqueous humor from the eyeball 76 to influence the intraocular pressure.The valve 91 is ideally pressure sensitive and uni-directional, and maybe comprised of a thin membrane of silicone or similar material. Thevalve 91 is positioned between the filter 52 and the apertures 19 withineither the central chamber 42 of the outlet assembly 26 or the chamber57 of the one-piece outlet assembly 27. In this position, aqueous humorinitially flows through the filter 52 before reaching the valve 91.Alternatively, the relative positions of the filter 52 and valve 91 canbe reversed so that aqueous humor initially flows through the valve. Asufficient amount of aqueous humor pressure (determined by theintraocular pressure) exerted on valve 91 will cause valve 91 to deform,allowing aqueous humor to flow into the outlet assembly 26 or one-pieceoutlet assembly 27 and on to the surface of the eyeball 76. Valves ofdifferent levels of intraocular pressure resistance may be utilizedwithin drainage apparatus 20 or 25 depending on the desiredpostoperative level of intraocular pressure within the eyeball 76.

Drainage apparatus 20 and 25 function to drain aqueous humor from theanterior chamber of an eyeball 76 to the external surface of the eyeball76. Drainage apparatus 20 or 25 is inserted in an eyeball 76 such thatthe first end 50 of the inlet assembly 24 is held within the anteriorchamber 80 of the eyeball 76, the tube 22 lies subconjunctivally,conforming to the external curvature of the eyeball 76, and the outletassembly 26 or one-piece outlet assembly 27 is positioned above theexternal surface of the eyeball 76. Aqueous humor from the anteriorchamber 80 of the eyeball 76 enters the opening 32 of the first end 50of the inlet assembly 24. The aqueous humor flows through the inletassembly 24 and into the tube 22. The tube 22 conducts the aqueous humorinto the outlet assembly 26 or one-piece outlet assembly 27. As theaqueous humor flows into the outlet assembly 26 or one-piece outletassembly 27, the aqueous humor passes through a filter 52 and perhapsalso through a valve 91. The filter functions to provide resistance tothe flow of aqueous humor when used alone. If coupled with a valve, thevalve instead provides this resistance by having an opening and closingpressure. After flowing through the filter 52 with or without valve 91,the aqueous humor flows through the outlet assembly 26 or one-pieceoutlet assembly 27 and drains onto the exterior surface of the eyeball76.

The present invention also discloses an apparatus and method forinserting drainage apparatus 20 or 25 into an eyeball 76. FIG. 8illustrates an inserting apparatus 56 which can be used to insert eitherembodiment of drainage apparatus 20 or 25 into an eyeball 76. Theinserting apparatus 56 is designed to greatly simplify insertion ofdrainage apparatus 20 or 25 into an eyeball 76 so as to minimize theduration and invasiveness of the insertion procedure.

As shown in FIGS. 8 and 9, the inserting apparatus 56 is comprised of aninsertion prong 58 attached to a first handle 60. The insertion prong 58has an insertion point 62. The insertion prong 58 also defines anaperture 64 wherein a second prong 66 is slideably received. As shown inFIG. 9, both the insertion prong 58 and the second prong 66 have anopening formed in their upper surface allowing for drainage apparatus 20or 25 to be received and seated prior to insertion into the eyeball 76.The second prong 66 is attached to a second handle 68 by means of afirst hinge 70. The second handle 68 is attached to the first handle 60by means of a second hinge 72. When the first handle 60 is held inplace, the second handle 68 is pushed towards the first handle 60,causing a rotation at the second hinge 72 such that the second handle 68will push the second prong 66 toward the insertion point 62.

The process of inserting drainage apparatus 20 or 25 into an eyeball 76with the inserting apparatus 56 is illustrated in FIG. 10. As shown inFIG. 14, a pericardial patch 90 is secured via suturing, tissue adhesive(glue) or other commonly known means around the tube 22 and insertionplate 74 of drainage apparatus 20 or 25. In addition to pericardium,patches may be fashioned of sclera, dura mater, fascia lata, or similarmaterial. Drainage apparatus 20 or 25 is then seated within theinserting apparatus 56 such that the beveled tip 28 of the inletassembly 24 is oriented towards the insertion point 62 of the insertionprong 58. As shown in FIG. 9, the outlet assembly 26 or one-piece outletassembly 27 is seated along the upper external aspect of the insertionprong 58. The distal end of the second prong 66 is positioned adjacentto the anterior aspect of the insertion plate 74. FIG. 10 illustratesthe position of the inserting apparatus 56 and drainage apparatus 20 or25 at insertion into an eyeball 76, said eyeball 76 having an iris 78,an anterior chamber 80, a conjunctival layer 82 and a limbus 86. Anincision is initially made in the conjuntival layer 82. The insertionpoint 62 of the insertion prong 58 and the second prong 66 are guidedthrough this incision and pushed beneath the conjunctival layer 82 tothe point at which the insertion point 62 and the beveled tip 28 of theinlet assembly 24 reaches the external boundary of the limbus 86. Theinsertion point 62 of the insertion prong 58 may also be driven throughthe conjunctival layer 82 without an initial incision. In some eyeballs76 with scarring between the conjunctival layer 82 and the underlyingepiscleral surface, blunt-tipped scissors can be inserted through theconjuncival incision to bluntly spread tissues to form a space betweenthe conjunctival layer 82 and the episcleral surface. Alternatively,fluid (such a balanced salt solution) or a viscoelastic substance can beinjected into this space to separate the conjunctival layer 82 from theepiscleral surface. When properly aligned at limbus 86 with theinsertion prong 58 and the second prong 66 positioned parallel to theplane of the iris by raising the end of the insertion device oppositethe insertion point 62, the insertion point 62 is driven through thelimbal tissue into the anterior chamber 80. Prior to driving insertionpoint 62 into the anterior chamber 80, viscoelastic material, if needed,can be injected into the anterior chamber 80 through a separate stabincision through the peripheral cornea. After the insertion point 62enters the anterior chamber 80, the second handle 68 is drawn towardsthe first handle 60, causing the second prong 66 to push against theanterior aspect of the insertion plate 74 and drive the beveled tip 28of the inlet assembly 24 through the limbus 86 into the anterior chamber80. The opening 32 of the inlet assembly 24 may then be secured in placewithin the anterior chamber 80 by the anchor 30, which rests against theangle or corneal endothelium in the anterior chamber 80. In addition,the insertion plate 74 rests against the external surface of the limbus86 and also functions to hold the inlet assembly 24 in proper position.A plurality of anchor flanges may also be formed upon the inlet assembly24 to accommodate varying limbal thicknesses. Alternatively, thedistance between anchor 30 and insertion plate 74 can be varied allowingthe surgeon to choose the appropriate inlet assembly 24 according to thelimbal thickness.

Once the inlet assembly 24 has been properly positioned, the insertingapparatus 56 is removed, leaving the drainage apparatus 20 or 25 inplace as shown in FIG. 12. As illustrated in FIG. 12, once in position,the tube 22 lies comfortably on the episcleral surface, and conforms tothe curvature of the eyeball 76. In this position, the conjunctivallayer 82 covers the pericardial patch 90 and tube 22. The pericardialpatch 90 attached to the tube 22 serves to protect the conjunctivallayer 82 from eventual erosion caused by the tube 22 or the insertionplate 74. As shown in both FIG. 12 and FIG. 5, the outlet assembly 26 isideally situated along the external ocular surface of the eyeball 76 inthe conjunctival cul-de-sac, between the eyeball 76 and the upper eyelid85 or lower eyelid 84. When inserted in this fashion, aqueous humor isdirected from the anterior chamber 80 of the eyeball 76 to the tear filmsurface of the eyeball 76.

If it is necessary to secure and stabilize the outlet assembly 26 or theone-piece outlet assembly 27, a suture can be used to fix it to theunderlying conjuntival layer 82. This suture can be passed through theperiphery of the outlet assembly 26 or the one-piece outlet assembly 27and through the conjunctival layer 82 only, or through both theconjunctival layer 82 and episcleral tissue. Alternatively, fixation ofthe outlet assembly 26 or the one-piece outlet assembly 27 can beaccomplished with tissue glue. Another means of fixation would be tocoat the posterior aspect of the inner member 36 of the outlet assembly26 or the posterior aspect of the second member 31 of the one-pieceoutlet assembly 27 with hydroxyapatite or similar material. If theepithelium of the conjunctival layer 82 underlying the outlet assembly26 or the one-piece outlet assembly 27 is abraded, the conjunctiva willadhere to the hydroxyapatite on the posterior aspect of either the innermember 36 or the second member 31.

Another embodiment of the inserting apparatus 77 is illustrated in FIG.15. The inserting apparatus 77 is designed to be used specifically forinsertion of drainage apparatus 25. This embodiment is used to insertthe inlet apparatus 24 and tube 22 of drainage apparatus 25 into theeyeball 76, allowing the one-piece outlet assembly 27 to be attached tothe second end 55 of the tube 22 after insertion.

As shown in FIG. 15, the inserting apparatus 77 comprises a trocar 73having an incision end 79 and secured within an outer cylinder 71 at itsopposite end. The outer diameter of the trocar 73 is slightly smallerthan the inner diameter of the tube 22. The outer cylinder 71 has anopen end 75 beyond which the incision end 79 of the trocar 73 extends.The outer cylinder 71 has an inner diameter slightly larger than theouter diameter of the tube 22. A pericardial patch 90 is secured aroundthe tube 22 and the insertion plate 74 as described earlier. The tube 22and inlet assembly 24 are then inserted over the trocar 73 within theouter cylinder 71 by inserting the incision end 79 through the secondend 55 of the tube 22 so that the incision end 79 passes through thetube and protrudes slightly beyond the opening 32 of the inlet assembly24. In this position, the incision end 79 is situated in line with thebeveled tip 28 of the inlet assembly 24 and the inlet assembly 24protrudes beyond the distal end of the outer cylinder 71 but stillsurrounds the incision end 79 of the trocar 73. The insertion plate 74is positioned against the open end 75 of the outer cylinder 71.

An incision is first made in the conjuntival layer 82 with either ascissors or with the incision end 79 of the trocar 73, and the inletassembly 24, tube 22, outer cylinder 71 and trocar 73 are then guidedthrough this incision and pushed beneath the conjunctival layer 82 tothe point at which the incision end 79 of the trocar 73 reaches theexternal boundary of the limbus 86. In certain eyeballs, theconjunctival layer 82 may need to be separated from the underlyingepiscleral tissue with blunt dissection, fluid, or viscoelastic materialas previously described. At this point, the outer cylinder 71 and trocar73 are pushed forward with an orientation parallel to the plane of theiris, causing the incision end 79 of the trocar 73 to pierce through thelimbus 86. This also causes the outer cylinder 71 to press against theinsertion plate 74 and drive the beveled tip 28 of the inlet assembly 24through the limbus 86 into the anterior chamber 80. The opening 32 ofthe inlet assembly 24 may then be secured in place within the anteriorchamber 80 as previously described. The outer cylinder 71 and trocar 73are then removed, and the tube 22 remains in position subconjunctivallyas previously described.

The second end 55 of the tube 22 exits through the initial incision ofthe conjunctival layer 82 several millimeters posterior from the limbus86. The one-piece outlet assembly 27 is then attached to the second end55 of the tube 22 by attaching a plunger or similar suctioning device 54to the external surface of the first member 29. The coupling mechanism33 of the one-piece outlet assembly 27 is then guided into position overthe second end 55 of the tube 22. Once in place, manual pressure isapplied to seat the the coupling mechanism 33 into the second end 55 ofthe tube 22. The one-piece outlet assembly 27 lies in the same positionas the outlet assembly 26 in FIG. 5 and 12, along the external ocularsurface of the eyeball 76 in the conjunctival cul-de-sac between theeyeball 76 and the upper eyelid 85 or lower eyelid 84. When inserted inthis fashion, aqueous humor is directed from the anterior chamber 80 ofthe eyeball 76 to the tear film surface of the eyeball 76.

The present invention also provides for removal and replacement of thefilter 52 and/or valve 91 from drainage apparatus 20 or 25. This featureallows for the rate of outflow of aqueous humor from the anteriorchamber 80 of the eyeball 76 through drainage apparatus 20 or 25 to bepost-surgically adjusted in a predictable manner. In drainage apparatus20, this process involves removing and replacing the outer member 34which houses the filter 52 and/or valve 91 in the central chamber 42. Inorder to remove and replace the outer member 34 and filter 52, theoutlet assembly 26 must first be stabilized. This is accomplished by useof the grasping apparatus 41 illustrated in FIG. 13. The graspingapparatus 41 is comprised of two elongated members 43, joined at theirproximal end 47, which taper to form an opposable grasping structure 45at their distal end. This opposable grasping structure 45 is shaped tomatch the external contour of the second end 55 of the tube 22, therebyallowing a user to grasp the second end 55 of the tube 22 so as tosecure the outlet assembly 26 as illustrated in FIG. 7. Once the outletassembly 26 is secured, the outer member 34 may be removed from theinner member 36 by cutting the superficial aspect of the central chamber42 of the outer member 34 with a scalpel or other surgical cutting tooland removing it from the inner member 36 with a forceps. The flange 40must also be removed from the groove 44 of the central cavity 46. Thedesign of drainage apparatus 20 allows for the outer member 34 to beeasily removed in this manner without damaging the inner member 36. Oncethe outer member 34 is removed, a new outer member 34 and filter 52 canbe attached to the inner member 36. As illustrated in FIG. 7, a plungeror similar suctioning device 54 is attached to the external surface of areplacement for the outer member 34, which allows the outer member 34 tobe guided into place by aligning the central chamber 42 of the outermember 34 into the central cavity 46 of the inner member 36. Once inplace, manual pressure is applied to seat the flange 40 of the centralchamber 42 within the groove 44 of the central cavity 46. Once thisattachment is made, the plunger or similar suctioning device 54 isremoved from the outer member 34, leaving the outer member 34 in place.Alternate methods for removing and replacing the outer member 34 fromthe outlet assembly 26 may also be used.

Removal and replacement of the filter 52 and/or valve 91 in drainageapparatus 25 is accomplished through the removal and replacement of theone-piece outlet assembly 27. The grasping apparatus 41 is used to graspthe second end 55 of the tube 22. Once the second end 55 of the tube 22is secured, the one-piece outlet assembly 27 may be removed bysectioning it centrally with a scalpel or other surgical cutting device.A forceps may be used to grasp the one-piece outlet assembly 27 eithercentrally or more peripherally as necessary to help facilitate thisprocess. The method for inserting a replacement one-piece outletassembly 27 is similar to the procedure described above. A plunger orsimilar suctioning device 54 is attached to the external surface of thefirst member 29 of a replacement for the one-piece outlet assembly 27,and the coupling mechanism 33 of the one-piece outlet assembly 27 isguided into position over the second end 55 of the tube 22. Once inplace, manual pressure is applied so as to seat coupling mechanism 33into the second end 55 of the tube 22. The plunger or similar suctioningdevice 54 is then removed. Alternate methods for removing and replacingthe one-piece outlet assembly 27 from drainage apparatus 25 may also beemployed.

The method to change filters in drainage apparatus 20 and 25 disclosedherein as a means to predictably control and regulate the level ofintraocular pressure in an eyeball 76 without invasive surgery is anovel feature of the present invention. This feature allows one topredictably control the flow of aqueous humor out of the anteriorchamber 80 of an eyeball 76 to achieve a predetermined postoperativetarget intraocular pressure. If the postoperative intraocular pressureis unacceptably high or low, the current filter 52 with or without valve91 can be replaced with a filter 52 with or without valve 91 to increaseor decrease the flow of aqueous humor out of the eyeball 76, thusreducing or increasing the intraocular pressure in the eyeball 76.

The outlet assembly 26 of drainage apparatus 20 is designed so that theimplant site, the central cavity 46 and the filter 52 and/or valve 91are surrounded by the outer member 34 and inner member 36, and are notdirectly exposed to the external surface of the eyeball 76. The same istrue with drainage apparatus 25, wherein the first member 29 and secondmember 31 surround the implant site and the filter 52 and/or valve 91.This feature of drainage apparatus 20 and 25 greatly reduces thepossibility of foreign material entering and clogging drainage apparatus20 or 25, subsequently hindering or negating its function. In addition,a filter 52 with appropriate pore diameter presents an absolute barrieragainst bacterial infiltration of drainage apparatus 20 or 25,preventing the possibility of an intraocular infection. The presentinvention may also incorporate a layer of hydroxyapatite or similarmaterial around the second end 55 of the tube 22 to stimulate the growthof the surrounding conjunctival layer 82 into the external surface ofthe tube 22, thereby providing a barrier around the external aspect ofdrainage apparatus 20 or 25.

The use of drainage apparatus 20 and 25, and inserting apparatus 56 and77 provide tremendous advantages over the prior art. Other drainagedevices and surgical techniques designed to decrease intraocularpressure and treat glaucoma are invasive and lengthy procedures,requiring multiple incisions into the eyeball. Patients often face longpostoperative recovery periods following such procedures. Other drainagedevices in the art are also very difficult to properly insert, andoperate to drain aqueous humor into a bleb or fibrous capsule which canscar and cease to function over time requiring additional surgery tocorrect. Inserting apparatus 56 and 77 provide a greatly simplifiedprocedure for insertion of drainage apparatus 20 and 25, requiring onlyone incision in the conjunctival layer 82, and in certain instances noincisions at all. Drainage apparatus 20 or 25 also drains aqueous humorout of the eyeball entirely, negating the need for the creation ofeither a fibrous capsule or a bleb. Since the insertion procedure forthe present invention is greatly simplified, the operating and recoverytime for the patient is considerably shortened. The insertion procedurefor the present invention is far less invasive than other surgicalprocedures currently used to increase aqueous humor drainage or insertdrainage devices. A significant advantage of the present inventioncompared to commercially available devices is that the outcome of thesurgical procedure is reliably predictable because it is independent ofthe vagaries of wound healing. The possibilities of insufficient woundhealing leading to hypotony, and excessive healing resulting in failureare eliminated. In addition, the convex lens shape of the outletassembly 26 and one-piece outlet end 27 makes the use of drainageapparatus 20 or 25 comfortable for the patient.

Optimally, the inlet assembly 24 of the drainage apparatus 20 and 25 isformed from Silastic® material. Alternatively, a hard plastic, such aspolymethyl methacrylate (PMMA), a durable glass or surgical metal, suchas surgical steel, may be required. The material from which the inletassembly 24 is comprised may need to be resilient to facilitate theinsertion procedure. A hard, resilient material would enable theinclusion of optional inlet holes 38 distal to the opening 32 in theevent that the opening 32 becomes occluded with intraocular tissue. Suchholes 38 would also reduce the possibility of the opening 32 becomingoccluded during the use of drainage apparatus 20 or 25. However, thedesign of the insertion point 62 of inserting apparatus 56 is sufficientto pierce the limbus 86 so as to allow the inlet assembly 24 to beproperly positioned within the anterior chamber 80, without necessarilyrequiring a hard material for the inlet assembly 24. Likewise, theincision end 79 of the trocar 73 of inserting apparatus 77 may negatethe need for a hard material for the inlet assembly 24. A softermaterial for the inlet assembly 24 would reduce the possibility ofdamage to intraocular tissues such as the cornea, iris or lens.

The tube 22 is optimally formed from a highly durable yet flexiblematerial, such as Silastic® or silicone. The tube 22 must be flexible,but should not be easily ruptured, bent or kinked so as to stop the flowof aqueous humor or hinder the drainage function of the drainageapparatus 20 or 25. The external surface of the tube 22, particularlythe area nearest the outlet assembly 26 or 27, is optimally coated witha material such as hydroxyapatite so as to enable the growth of thesurrounding conjunctival layer 82 into the external surface of the tube22, providing an absolute barrier between the outside surface of thetube 22 and the conjunctival layer 82 surrounding the tube 22 on theouter surface of the eyeball 76. The filter 52 may be formed frompolycarbonate, although many other materials would also be suitable. Andas discussed earlier, valves 91 for use in the drainage apparatus 20 or25 may be formed from silicone or Silastic® material.

Other suitable filter types, valves and materials for the tube 22, inletassembly 24, outlet assembly 26, and one-piece outlet assembly 27 ofdrainage apparatus 20 or 25 may be used in accordance with the presentinvention and will be apparent to those of skill in the art.

Use of the present invention as a means to treat glaucoma will allow formaintenance of a predictable post-surgical intraocular pressure whichcan be further modified as necessary to achieve a desired result. Thepresent invention is comfortable and durable, and reduces thepossibility of further damage to the optic nerve and visual lossresulting from excessively high or low intraocular pressure. The presentinvention also lessens the need for additional treatments or surgicalprocedures and their inherent risks, procedures which may result infurther damage to vision. The insertion procedure for the presentinvention is far less invasive than other surgical procedures, includingthe procedures for inserting other drainage devices currently used toincrease aqueous humor drainage. In addition, the present inventionlimits the risk of infection for the patient by providing an absolutebarrier against infection compared with the cystic, thin-walled blebsthat often occur with standard filtration procedures performed inconjunction with anti-scarring agents such as mitomycin C or5-fluorouracil.

1. An apparatus to reduce intraocular pressure in an eyeball,comprising: an inlet assembly, a tube and an outlet assembly, said tubebeing disposed between said inlet assembly and said outlet assembly,wherein said outlet assembly is positioned at the external surface ofthe eyeball; a flange adapted for securing said inlet assembly withinthe anterior chamber of the eyeball; and means for controlling the flowof aqueous humor through said tube from said anterior chamber of theeyeball to said external surface of the eyeball, whereby said aqueoushumor may flow from said anterior chamber of the eyeball to the externalsurface of the eyeball.
 2. The apparatus of claim 1 wherein said outletassembly comprises a member shaped to correspond to the externalcurvature of an eyeball and covers any point of ingress into theeyeball.
 3. The apparatus of claim 1 wherein said outlet assemblycomprises two members shaped to correspond to the external curvature ofan eyeball held in relative proximity to each other and covers any pointof ingress into the eyeball.
 4. The apparatus of claim 1 wherein saidmeans for controlling the flow of aqueous humor is contained within saidoutlet assembly.
 5. The apparatus of claim 1 wherein said means forcontrolling the flow of aqueous humor comprises a replaceable filter. 6.The apparatus of claim 1 wherein said means for controlling the flow ofaqueous humor comprises a replaceable valve.
 7. The apparatus of claim 1wherein said means for preventing infection comprises a replaceablefilter.
 8. The apparatus of claim 1 wherein said means of fixation ofthe outlet assembly would be to coat the posterior aspect of the innermember of the outlet assembly with hydroxyapatite or similar material.If the epithelium of the conjunctival layer underlying the outletassembly is abraded, the conjunctiva will adhere to the hydroxyapatiteon the posterior aspect of the inner member of the outlet assembly. 9.The apparatus of claim 1 wherein said means of replacing the outletassembly including the replaceable filter and/or valve comprises the useof a plunger or similar suctioning device to the external surface of theoutlet assembly.
 10. An apparatus to reduce intraocular pressure withinan eyeball, comprising: a tube having an inlet assembly and an outletassembly, said outlet assembly being positioned at the external surfaceof the eyeball; a flange adapted for securing said inlet assembly withinthe anterior chamber of the eyeball; and means for controlling the flowof aqueous humor through said tube from said anterior chamber of theeyeball to said external surface of the eyeball, whereby said aqueoushumor may flow from said anterior chamber of the eyeball to the externalsurface of the eyeball.
 11. The apparatus of claim 10 wherein saidoutlet assembly comprises a member shaped to correspond to the externalcurvature of an eyeball and covers any point of ingress into theeyeball.
 12. The apparatus of claim 10 wherein said outlet assemblycomprises two members shaped to correspond to the external curvature ofan eyeball held in relative proximity to each other and covers any pointof ingress into the eyeball.
 13. The apparatus of claim 10 wherein saidmeans for controlling the flow of aqueous humor is contained within saidoutlet assembly.
 14. The apparatus of claim 10 wherein said means forcontrolling the flow of aqueous humor comprises a replaceable filter.15. The apparatus of claim 10 wherein said means for controlling theflow of aqueous humor comprises a replaceable valve.
 16. The apparatusof claim 10 wherein said means for preventing infection comprises areplaceable filter.
 17. The apparatus of claim 10 wherein said means offixation of the outlet assembly would be to coat the posterior aspect ofthe inner member of the outlet assembly with hydroxyapatite or similarmaterial. If the epithelium of the conjunctival layer underlying theoutlet assembly is abraded, the conjunctiva will adhere to thehydroxyapatite on the posterior aspect of the inner member of the outletassembly.
 18. The apparatus of claim 10 wherein said means of replacingthe outlet assembly including the replaceable filter and/or valvecomprises the use of a plunger or similar suctioning device to theexternal surface of the outlet assembly.
 19. A surgical method to reduceintraocular pressure within an eyeball through the use of a drainageapparatus having an inlet assembly, an outlet assembly and a tubedisposed between said inlet assembly and said outlet assembly, saiddevice having means for controlling the flow of aqueous humor throughsaid tube, comprising the steps of: inserting said inlet assembly ofsaid drainage apparatus into the anterior chamber of said eyeball;securing said inlet assembly of said drainage apparatus within saidanterior chamber of said eyeball; securing said outlet assembly at theexternal surface of said eyeball, and controlling the rate of aqueoushumor flowing from said anterior chamber of said eyeball to saidexternal surface of said eyeball.
 20. The method of claim 19 whereinsaid means for controlling the amount of aqueous humor flowing from saidanterior chamber comprises removing and replacing a filter.
 21. Themethod of claim 19 wherein said means for controlling the amount ofaqueous humor flowing from said anterior chamber comprises removing andreplacing a valve.
 22. A device for use to surgically implant a drainageapparatus in an eyeball comprising: a first elongated member movablyattached to a first handle, said first elongated member defining anaperture, wherein said first elongated member contains a sharpened end;a second elongated member slideably received within said aperture ofsaid first elongated member, said second elongated member movablyattached to a second handle; said first handle and said second handlebeing movably attached, such that movement of said second handleforcibly moves said second elongated member within said aperture of saidfirst elongated member, whereby said second elongated member may pushsaid drainage apparatus through the conjunctival layer of said eyeballinto the anterior chamber of said eyeball.
 23. An alternative device foruse to surgically implant a drainage apparatus in an eyeball comprising:a trocar having an incision end and secured within an outer cylinder atits opposite end; the outer cylinder has an open end beyond which theincision end of the trocar extends; the tube and inlet assembly of thedrainage device are inserted over the trocar within the outer cylinderby inserting the incision end through the second end of the tube so thatthe incision end passes through the tube and protrudes slightly beyondthe opening of the inlet assembly; the insertion plate is positionedagainst the open end of the outer cylinder; the inlet assembly, tube,outer cylinder and trocar are guided through a conjunctival incision andpushed beneath the conjunctival layer to the limbus; the incision end ofthe trocar is pierced through the limbus with the outer cylinderpressing against the insertion plate to drive the beveled tip of theinlet assembly through the limbus into the anterior chamber of saideyeball.
 24. A device for removing and replacing a filter in a drainageapparatus comprising: a first elongated member having a terminal end;second elongated member having a terminal end and being opposablyattached to said first elongated member; grasping means formed withinsaid terminal end of said first elongated member and said terminal endof said second elongated member, whereby said first elongated member andsaid second elongated member are capable of being manipulated to graspan object.
 25. An apparatus for reducing intraocular pressure in aneyeball, comprising: a tube, said tube having a first end and a secondend; an inlet assembly, said inlet assembly having a first end and asecond end, said first end of said inlet assembly adapted for insertioninto the anterior chamber of an eyeball, said second end of said inletassembly attached to and in fluid communication with said first end ofsaid tube; a flange extending from said inlet assembly and adapted forsecuring said first end of said inlet assembly within said anteriorchamber; an outlet assembly attached to and in fluid communication withsaid second end of said tube, said outlet assembly positioned on theexternal surface of said eyeball; and means for adjustably controllingthe rate of flow of aqueous humor from said anterior chamber to saidexternal surface of said eyeball.
 26. The apparatus of claim 25, saidoutlet assembly comprising a first member shaped to generally correspondto the external curvature of said external surface of said eyeball, saidfirst member covering the point of insertion of said first end of saidinlet assembly into the conjunctival layer of said eyeball, a secondmember in spaced relation with said first member, said first and secondmembers thereby defining a void through which aqueous humor may flow tosaid external surface of said eyeball.
 27. The apparatus of claim 25,wherein said means for adjustably controlling the rate of flow ofaqueous humor is contained within said outlet assembly.
 28. Theapparatus of claim 25, wherein said means for adjustably controlling therate of flow of aqueous humor comprises a replaceable filter.
 29. Theapparatus of claim 25, wherein said means for adjustably controlling therate of flow of aqueous humor comprises a replaceable valve.
 30. Theapparatus of claim 25, wherein said means for adjustably controlling therate of flow of aqueous humor is adapted to be replaceable withoutremoval of said first end of said inlet assembly from said anteriorchamber of said eyeball.
 31. The apparatus of claim 25, wherein saidtube and said inlet assembly are formed as an integral unit.
 32. Adevice for surgically implanting a drainage apparatus in an eyeball,comprising: a first handle; a second handle, said second handlepivotally attached to said first handle; a first elongated memberextending from said first handle, said first elongated member definingan aperture and further defining a slot adapted for receiving a drainageapparatus therein, said first elongated member comprising a sharpenedend; a second elongated member, said second elongated member slidablyreceived within said aperture of said first elongated member andpivotally attached to said second handle, whereby movement of saidsecond handle and said second elongated member towards said sharpenedend of said first elongated member urges said drainage apparatus intothe anterior chamber of said eyeball.
 33. The device of claim 32,wherein said first elongated member is adapted to be inserted beneaththe conjunctival layer of said eyeball.
 34. The device of claim 33,wherein said sharpened end of said first elongated member is adapted topierce the limbus of said eyeball.
 35. A device for surgicallyimplanting a drainage apparatus in an eyeball, comprising: a handle; anelongated member extending from said handle, said elongated memberdefining an aperture; a trocar attached within said aperture of saidelongated member and extending therefrom, said trocar comprising asharpened end, wherein said trocar is adapted to be received within saiddrainage apparatus; whereby said elongated member and said trocar may bemanipulated to urge the drainage apparatus into the anterior chamber ofsaid eyeball.
 36. The device of claim 35, wherein said elongated memberand said trocar are adapted to be inserted beneath the conjunctivallayer of said eyeball.
 37. The device of claim 36, wherein saidsharpened end of said trocar is adapted to pierce the limbus of saideyeball.
 38. A method for treating glaucoma, comprising: Inserting adrainage apparatus into an eyeball, said drainage apparatus comprising atube having a first end and a second end, an inlet assembly adapted forinsertion into the anterior chamber of an eyeball and attached to and influid communication with said first end of said tube, said inletassembly further comprising a flange extending therefrom, an outletassembly attached to and in fluid communication with said second end ofsaid tube, said outlet assembly positioned on the external surface ofsaid eyeball and comprising means to adjustably control the rate of flowof aqueous humor through said drainage apparatus; Securing said inletassembly within said anterior chamber of said eyeball by positioningsaid flange against the corneal endothelium of said anterior chamber,whereby said aqueous humor from said anterior chamber flows through saiddrainage apparatus to said external surface of said eyeball; Monitoringthe intraocular pressure of said eyeball; and Adjusting said means toadjustably control the rate of flow of aqueous humor to vary the rate offlow of said aqueous humor through said drainage apparatus, therebyvarying the intraocular pressure in said eyeball.
 39. The method ofclaim 38, wherein said flange is positioned against the angle of saideyeball.
 40. The method of claim 38, wherein adjusting said means toadjustably control the rate of flow of aqueous humor comprises removingand replacing a valve.
 41. The method of claim 38, wherein adjustingsaid means to adjustably control the rate of flow of aqueous humorcomprises removing and replacing a filter.